Manufacturing method and manufacturing apparatus of magnetoresistance elements

ABSTRACT

A manufacturing method of a magnetoresistance element having a pinned magnetic layer, a non-magnetic intermediate layer, and a free magnetic layer, the method includes forming at least one thin film of the non-magnetic intermediate layer and the free magnetic layer at a pressure of 8.0×10 −3  Pa or less in the vicinity of a substrate using a sputtering apparatus. The apparatus includes a vacuum chamber in which a cathode and a substrate holder are arranged, a first exhausting apparatus connected to an exhausting port of the vacuum chamber, a gas introduction mechanism to introduce a gas toward the target, a first pressure regulator to cause a pressure difference between a target space and a center space outside the target space, a second pressure regulator to cause a pressure difference between the center space and a substrate space, and a second exhausting apparatus to exhaust the center space.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the priority of JP 2004-272230, filed inJapan on Sep. 17, 2004, the entire contents of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a manufacturing method and amanufacturing apparatus of a magnetoresistance element, and inparticular to the manufacturing method of magnetoresistance elementshaving excellent magnetic characteristics like a magneto-resistanceratio (MR ratio).

DESCRIPTION OF RELATED ART

Magnetoresistive elements such as a Giant Magneto Resistance (GMR)element and a Tunnel Magnetic Resistance (TMR) element have amultilayered structure which is composed of an anti-ferromagnetic layer,a pinned magnetic layer, a non-magnetic intermediate layer, and a freemagnetic layer to have a large magneto-resistance ratio (MR ratio), andtherefore are practically used for high density magnetic devices such asa magnetic head and a nonvolatile random access memory (MRAM).

In recent years, the recording density of magnetic devices has greatlyincreased. As a result, the magnetic head, for example, is required tohave higher output and high-speed operation. For this reason, a varietyof examinations on, for example, the film quality, the processing methodof each layer and the structure of multi-layers have been carried out tofurther improve the magnetic characteristics. In the case of, e.g., theGMR element, it is reported that the MR ratio can be enhanced by theinsertion of a very thin oxide layer NOL (Nano-Oxide Layer) having athickness of 1 nm or less between films forming the pinned magneticlayer.

Moreover, the MR ratio is also enhanced by carrying out the plasmaprocessing on the surface of a thin film of the anti-ferromagnetic layerand the non-magnetic intermediate layer (JP2003-86866A).

SUMMARY

As described, the MR ratio can be enhanced to some extent by insertingan oxide layer NOL between the multi-layers of the GMR element, or bycarrying out plasma processing. Since the GMR element is composed ofvery thin metallic films with a thickness of nanometer level, the GMRcharacteristics depend on the quality, thickness uniformity and flatnessof each metallic thin film. Therefore, in order to further enhance GMRcharacteristics, it is inevitable to improve the film properties foreach film, and to establish a film forming method which enables theformation of such films with sufficient reproducibility.

Then, the present inventors examined various film forming methods andconditions to provide the multilayered structure of nanometer-order thinfilms, and found that the quality and flatness of each film had a closerelation with the forming conditions, especially pressure during thesputtering. That is, the MR ratio was varied with the sputteringpressure. In parallel with such examinations, the present inventors havestudied a low-pressure sputtering apparatus, and developed a magnetronsputtering apparatus which makes a very low pressure of about 10⁻⁴ Pa inthe vicinity of a substrate while the plasma discharge is stablymaintained (JP 2003-77888).

The non-magnetic intermediate layer was formed at a low pressure of2.0×10⁻³ Pa or less using the low-pressure sputtering apparatus. Thefilm thus obtained was found to have higher properties. For example, thespecific resistance was decreased. The thickness uniformity and flatnessof the film were also improved, resulting in the increase of MR ratio.

This is also true in the case of MRAM and TMR element. The conventionalsputtering apparatuses cannot cope with the reproducible formation ofhigh quality films when the films to be stacked become as thin asone-atom or several-atom thickness.

An object of the present invention is to provide a manufacturing methodand a manufacturing apparatus of a magnetoresistance element tomanufacture, e.g., GMR elements and TMR elements having excellentmagnetic characteristics like magneto-resistance ratio (MR ratio).

According to one embodiment, a manufacturing method of the presentinvention for manufacturing a magnetoresistance element composed of apinned magnetic layer, a non-magnetic intermediate layer, and a freemagnetic layer, comprises forming at least one thin film of saidnon-magnetic intermediate layer and said free magnetic layer at apressure of 8.0×10⁻³ Pa or less in the vicinity of a substrate, by usinga sputtering apparatus.

The non-magnetic intermediate layer can be formed at a low pressure of8.0×10⁻³ Pa or less by using a magnetron sputtering method, whichimproves the MR ratio as well as the uniformity of the film thicknessand the flatness. As a result, the product yield of GMR and TMR elementsis greatly increased. This is also true for the film of free magneticlayer.

In one embodiment of this invention, the non-magnetic intermediate layeris a non-magnetic conductive layer such as a Cu film in the case of GMRelement, and a tunneling barrier layer such as an Al₂O₃ film in the caseof TMR element. Here, the sputtering apparatus comprises a vacuumchamber in which a cathode holding a target and a substrate holderholding said substrate are arranged, a first exhausting apparatusconnected to an exhausting port of said vacuum chamber, a gasintroduction mechanism to introduce a (process) gas to a target space inthe vicinity of a surface of said target, a first pressure regulator tocause a pressure difference between said target space and a center spacewhich lies outside said target space, a second pressure regulator tocause a pressure difference between said center space and a substratespace in the vicinity of a surface of said substrate, and a secondexhausting apparatus to exhaust said center space.

By using such a sputtering apparatus, it becomes possible to make thepressure near the substrate lower than 8.0×10⁻³ Pa. That is, the firstand second pressure regulator are arranged to cause the pressuredifference among the target space, the substrate space and the centerspace, and in addition the second exhausting apparatus is arranged toexhaust the center space. This construction reduces the amount of theprocess gas flowing toward the substrate and increases the pressuredifference between the target space and the substrate space. As aresult, it becomes possible to make the pressure near the substratelower while maintaining stable sputtering discharge.

The first pressure regulator is arranged to restrict the gas flowingfrom the target surface and its vicinity to the center space. The firstpressure regulator may be, for example, a tapered cylinder member whosediameter decreases toward the substrate, or a cylinder member whose endat the substrate side is covered with a plate having at least one hole.The member is arranged so as to surround the target.

With the construction of first regulator, the pressure can be set to alower value in the vicinity of the substrate. Particularly when thecylinder member whose end at the substrate side is covered with a platehaving a plurality of holes is employed, it is possible by adjusting thesize and length of holes to make the pressure much lower in the vicinityof the substrate and to improve the vertical incidence of sputteringparticles to the substrate.

The second pressure regulator can also have the same shape as the firstpressure regulator. Furthermore, the means can be constructed byarranging a partition member having at least one hole so as to dividethe inside of the vacuum chamber into a target side and a substrateside. Both the first and the second pressure regulator can be such apartition member.

In this invention, at least two pressure regulator are arranged.Therefore, three or more pressure regulator can be arranged according todemand.

As has been mentioned, by forming at least one thin film whichconstitutes the non-magnetic intermediate layer or the free magneticlayer at a pressure of 8.0×10⁻³ Pa or less, the MR ratio, the filmthickness uniformity, and the film flatness can be greatly improved,which makes it possible to manufacture high characteristic GMR elementsand TMR elements with a higher production yield.

Thus, the magnetic heads with high output and high sensitivity can beobtained to realize high-density hard discs and MRAM.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a magnetoresistance filmmanufacturing apparatus of Embodiment 1.

FIG. 2 is a schematic sectional view showing a magnetoresistance filmmanufacturing apparatus of Embodiment 2.

FIG. 3 is a schematic sectional view showing a low-pressure sputteringchamber.

FIG. 4 is a graph showing the relation between the MR ratio and thethickness of Cu film.

FIG. 5 is a schematic sectional view showing another low-pressuresputtering chamber.

FIG. 6 is a schematic sectional view showing another low-pressuresputtering chamber.

FIG. 7 is a schematic sectional view showing another low-pressuresputtering chamber.

FIG. 8 is a schematic sectional view showing another low-pressuresputtering chamber.

FIGS. 9A and 9B are multilayered structures of a GMR element and a TMRelement, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

-   -   Here, numeral 1 denotes vacuum chamber,    -   2 magnetron cathode,    -   3 target,    -   4 backing plate,    -   5 magnet unit,    -   6 insulating member,    -   7 substrate,    -   8 substrate holder,    -   9 gas introduction pipe,    -   11 first exhausting apparatus,    -   12 and 12′ second exhausting apparatus,    -   13 first pressure regulator,    -   13 a and 14 a hole,    -   14 second pressure regulator,    -   17 and 17′ exhausting port,    -   19 and 19′ main valve,    -   20 low-pressure sputtering chamber,    -   21 load lock chamber,    -   22 through 24 sputtering chamber,    -   25 oxidization chamber,    -   26 gate valve,    -   27 transfer chamber, and    -   28 robot.

The embodiment of this invention is explained below, based on thedrawings.

Embodiment 1

As an example of manufacturing methods of this invention, a method usedfor manufacturing a GMR element having a multilayered structure shown inFIG. 9A will be explained.

FIG. 1 is an apparatus suitably used for manufacturing themagnetoresistance element shown in FIG. 9A. The manufacturing apparatusis composed of a first sputtering chamber 22 for forming a buffer layerTa and an anti-ferromagnetic layer PtMn, a second sputtering chamber 23for forming a pinned magnetic layer (CoFe/Ru/CoFe), a low-pressuresputtering chamber 20 for forming a non-magnetic intermediate layer Cuat a low pressure of 10⁻³ Pa or less, a third sputtering chamber 24 forforming a free magnetic layer (CoFe/NiFe) and a passivation layer Ta, aload lock chamber 21 which stores cassettes holding a plurality ofsubstrates, and a transfer chamber 27 in which a robot 28 is installedto transfer a substrate. The chambers 20-24 are connected through gatevalves 26 to the periphery of the transfer chamber 27. In the sputteringchamber to which a gas supply system and at least one exhaustingapparatus are connected, at least one magnetron cathode equipped with atarget is arranged corresponding to the film to be formed.

Here, the low-pressure sputtering chamber 20 is explained with referenceto FIG. 3. The first through third sputtering chambers are conventionalsputtering chambers having well-known structure.

The low-pressure sputtering chamber 20 is constructed such that amagnetron cathode 2 which is composed of a Cu target 3, a backing plate4 and a magnet unit 5 is arranged facing a substrate holder 8 holding asubstrate 7 in a vacuum chamber 1, as shown in FIG. 3. There is provideda gas introduction pipe 9 on the target side of the vacuum chamber 1 todischarge a process gas toward the surface of the target 3, and isprovided an exhausting port 17 on the substrate holder side to attach afirst exhausting apparatus 11 (for example, a turbo molecular pump)through a main valve 19. The magnetron cathode 2 is fixed to the vacuumchamber 1 through an insulating member 6, and connected to a directcurrent power source or a high frequency power source (not illustrated).The gas introduction pipe 9 is connected to a gas supply system (notillustrated).

A first pressure regulator and a second pressure regulator are arrangedin order to cause a pressure difference in the vacuum chamber. That is,as the first pressure regulator 13, a cylinder member whose end on thesubstrate side is closed with a plate having a plurality of holes 13 ais arranged so as to surround the target. As the second pressureregulator 14, a partition plate with a plurality of holes 14 a isemployed to divide the inside of vacuum chamber 1. In addition, in thisembodiment, a second exhausting apparatus 12 is arranged to exhaust thecenter space, which is surrounded by the first pressure regulator andthe second pressure regulator.

For the first and the second pressure regulators, the holes 13 a, 14 aare preferably provided symmetrically around the central axis of target.The size of holes is 1-30 mm in diameter (preferably 5-20 mm). It ispreferable to make the holes of the second pressure regulator large ascompared with those of the first pressure regulator. There is noparticular restriction in the length of hole (or the thickness ofplate), but a length of about 5-20 mm is usually employed.

As mentioned above, the size and the number of the holes in the firstand second pressure regulators, and the number, the exhausting capacityand the position of the first and second exhausting apparatuses aresuitably selected, which makes it possible to realize the pressure of1.0×10⁻⁴ Pa near the substrate when the pressure near the target is setto, e.g., 1.0×10⁻² Pa.

It is also possible by adjusting the size and thickness of the holes toimprove the vertical incidence of sputtering particles onto thesubstrate.

Next, the manufacturing method of the GMR element shown in FIG. 9A willbe explained using the manufacturing apparatus of FIG. 1.

First, the cassette holding a lot of quartz glass substrates istransported into the load lock chamber 21, and the chamber is exhausted.The gate valves are opened so that the transfer robot 28 takes out asubstrate from the cassette and places it on the substrate holder of thefirst sputtering chamber 22. The inside of the sputtering chamber 22 isexhausted to a high vacuum. Then, Ar gas is introduced at a prescribedflow rate and a Ta buffer layer is formed on the SiO₂ plate. Similarly,a PtMn anti-ferromagnetic layer is formed thereon.

After that, the substrate is transferred to the chambers in the order ofthe second sputtering chamber 23, the low-pressure sputtering chamber20, and the third sputtering chamber 24 to form the thin films inrespective chambers. At the same time, the other substrates arecontinuously taken out from the cassette of the load lock chamber 21 andtransferred similarly to manufacture the GMR multilayered element. Aftera Ta passivation layer is formed, the substrate is returned to thecassette of the load lock chamber. Thus the substrates are placed in ahighly clean atmosphere while all films are formed, which prevents thefilm interfaces from contamination to obtain high quality GMR elements.

The film forming procedure in the low-pressure sputtering chamber 20 isexplained below. The substrate 7 on which the pinned magnetic layer hasalready been formed is transferred into the low-pressure sputteringchamber through the gate valve 26 and is placed on the substrate holder8. The gate valve 26 is closed and the vacuum chamber 1 is exhausted tohigh vacuum by the exhausting apparatuses 11, 12. After a predeterminedperiod, Ar gas is introduced at a predetermined flow rate from the gassupply system. Then, the high frequency power is supplied to the cathodefrom a high frequency power supply (not illustrated) to generate plasmadischarge. The main valve 19′ is adjusted to set the pressure in thevicinity of the target to about 1.0×10⁻² Pa, maintaining the plasmadischarge. Then, the main valve 19 is adjusted to set the pressure inthe vicinity of the substrate to a predetermined value of, e.g.,8.0×10⁻³ Pa or less.

Then, a shutter (not illustrated) is opened and a Cu film is formed onthe CoFe film of the substrate. When the film with a predeterminedthickness is formed, the power supply and the gas introduction arestopped. After the chamber is exhausted to high vacuum, the gate valve26 is opened. The robot 28 picks up the substrate 7 and transfers it tothe third sputtering chamber 24 to form the free magnetic layer and thepassivation layer thereon. In the mean time, another substrate, whichthe pinned magnetic layer has been formed in the second sputteringchamber 23, is transferred to the low-pressure sputtering chamber 20 tosimilarly form a Cu film.

Here, the experiment result is concretely explained. A GMR elementhaving the multilayered structure as shown in FIG. 9A was manufactured.The thickness of Cu film was 1.8-2.6 nm. When the Cu film was formed,the pressure was set to 1.0×10⁻² Pa near the target and 8.0×10⁻⁴ Pa nearthe substrate. In contrast, the pressure was set to 2.4×10⁻²-2.2×10⁻¹ Pawhen the other films were formed. The MR ratios of the GMR elements thusfabricated were measured and shown in FIG. 4. The comparison sample ofGMR element was also manufactured using the conventional apparatus. Inthis case, the Cu film was formed using the conventional sputteringchamber instead of the low-pressure sputtering chamber of FIG. 3. The MRratios of the GMR elements were also measured and summarized in FIG. 4.The pressure near the substrate (or the pressure of sputtering chamber)was set to 3.6×10⁻² Pa when the Cu film was formed in the conventionalsputtering chamber.

It is apparent from FIG. 4 that the MR ratio is improved by forming thenon-magnetic intermediate film using the low-pressure magnetronsputtering method. The difference becomes remarkable, as the Cu film isthinner. The Cu film formed in this embodiment has a high quality andexcellent thickness uniformity even in the case where the film is ultrathin.

When the Cu film of GMR film is 1.8 nm, the coercive force Hcf of thefree magnetic layer was decreased to 1.97×10 2 A/m from 2.17×10 2 A/m(comparison sample).

The Cu film with a thickness of 20 nm was formed at a sputteringpressure of 3.0×10⁻² Pa in the conventional sputtering chamber. Thespecific resistance of the Cu film thus obtained was 5.1 μΩcm. On theother hand, the specific resistance was decreased to 4.6 μΩcm when thepressure near the substrate was decreased to 3.0×10⁻³ Pa in thelow-pressure sputtering chamber.

As mentioned, the magnetic characteristics of the GMR element aregreatly improved by decreasing the sputtering pressure for thenon-magnetic intermediate layer from 3.6×10⁻² Pa to 8×10⁻⁴ Pa. Theimprovement of the magnetic characteristics may be explained as follows.That is, when the pressure near the substrate is made lower, the amountof sputtering gas such as Ar gas contained in the film is decreased toimprove the film quality. The substrate is hardly exposed to the plasmaunlike the conventional method. Furthermore, the surface roughness Ra isdecreased to improve the flatness of film.

The GMR element was also manufactured at a sputtering pressure of8.0×10⁻³ Pa for the non-magnetic intermediate layer. The result wasnearly the same as that formed at a sputtering pressure of 8.0×10⁻⁴ Pa.

Next, the Cu target was exchanged with the CoFe target or the NiFetarget for the free magnetic layer in the manufacturing apparatus ofFIG. 1, and a CoFe film (or NiFe film) of the free magnetic layer wasformed at a pressure of 8.0×10⁻³ Pa near the substrate in thelow-pressure sputtering chamber. The GMR element was manufactured in thesame manner as mentioned except for these film forming processes. The MRratio was increased by forming the CoFe film or NiFe film of the freemagnetic layer in the low sputtering chamber as compared with thecomparison samples described above. That is, it was found that themagnetic characteristics of GMR element can be improved by forming atleast one of the films which constitute the non-magnetic intermediatelayer and the free magnetic layer at a very low pressure.

In the low-pressure sputtering chamber shown in FIG. 3, the gasintroduction pipe is provided to discharge the gas toward the targetthrough one outlet. However, it is preferable to arrange a plurality ofgas outlets symmetrically to the target. The second exhausting apparatusis not restricted to one, and therefore a plurality of apparatuses canbe arranged.

Although the cylinder member is used for the first pressure regulator inFIG. 3, a partition plate 13 may be employed in the same way as shown inFIG. 5. In addition, another exhausting apparatus may be arranged toexhaust the target space in FIG. 5.

The cluster type manufacturing apparatus is employed in this embodiment.However the in-line type apparatus in which the chambers are linearlyarranged can be also employed.

Embodiment 2

In this embodiment, a manufacturing method of a TMR element shown inFIG. 9B will be explained by referring to a manufacturing apparatusshown in FIG. 2 which is preferably used for manufacturing the TMRelement.

The manufacturing apparatus is composed of a first sputtering chamber 22for forming a buffer layer Ta and an anti-ferromagnetic layer PtMn, asecond sputtering chamber 23 for forming a pinned magnetic layer(CoFe/Ru/CoFe), a low-pressure sputtering chamber 20 for forming analuminum film at a low pressure of 8.0×10⁻³ Pa or less for a tunnelbarrier layer use, an oxidation chamber 25 to oxidize the aluminum filmto form a tunnel barrier layer Al₂O₃, a third sputtering chamber 24 forforming a free magnetic layer (CoFe/NiFe) and a passivation layer Ta, aload lock chamber 21 which stores cassettes holding a plurality ofsubstrates, and a transfer chamber 27 in which a robot 28 is installedto transfer a substrate. These chambers 20-25 are connected through gatevalves 26 to the periphery of the transfer chamber 27. The structure ofa low-pressure sputtering chamber 20 is the same as that of Embodiment1.

The oxidation chamber 25 is equipped with an oxygen gas supply system(not illustrated) to introduce an oxygen gas onto a substrate to oxidizeonly the aluminum film formed on the pinned magnetic layer. Otheroxidation methods may also be employed. For example, the substrate isheated to a predetermined temperature and then oxidized, or thesubstrate is exposed to the oxygen plasma. A dense aluminum film, whichis flat, uniform and free of impurity mixing, is formed by thelow-pressure sputtering at a pressure of 8.0×10⁻³ Pa or less. Therefore,the oxidation of the aluminum film in the oxidation chamber provides ahigh quality barrier layer.

The film forming procedure of the TMR element is the nearly the same asthat of the GMR element. That is, at least one of the films constitutingthe tunneling barrier layer and the free magnetic layer of the TMRelement is formed by the low-pressure sputtering method, which canimprove the film quality and flatness. Thus the magnetic characteristicsof the TMR elements are improved as well as the GMR elements.

In this embodiment, the aluminum film is formed in the low-pressuresputtering chamber and then oxidized in the oxidation chamber to providethe A₂O₃ film used for the tunneling barrier film. But the Al₂O₃ filmcan be directly formed on the substrate by a reactive sputtering methodin which Ar gas containing oxygen gas is introduced to the low-pressurechamber, or by using an Al₂O₃ target.

In the present invention, the low-pressure sputtering chambers shown inFIGS. 6-8 are also preferably employed in addition to those shown inFIGS. 3 and 5.

In the sputtering chamber shown in FIG. 6, the first pressure regulator13 is a tapered, nozzle-shaped member arranged to surround the target 3.The second pressure regulator 14 is arranged outside the first pressureregulating member 13 and is composed of a tapered, nozzle-shaped memberand a cylinder attached to the end of the member.

Furthermore, an exhausting port 17′ which is communicated with the spacebetween the first and second pressure regulators (the center space) isprovided behind the magnetron cathode 2 and the second exhaustingapparatus (for example, turbo-molecular pump) 12 is attached to theexhausting port 17′ through a main valve 19′.

As mentioned, the first pressure regulator 13 is a tapered,nozzle-shaped member and the second pressure regulator 14 comprises thetapered, nozzle-shaped member and the cylinder in FIG. 6. One regulatormay have the shape of the other regulator or both regulators may havethe same shape. The exhausting capacity of second exhausting apparatus12 can be made smaller than the first exhausting apparatus 11. Theexhaust rates of first and second exhausting apparatuses, together withthe length and the degree of taper of the first and the second pressureregulators, are determined depending on the required pressure near thesubstrate.

The arrangement of these two pressure regulators can reduce the pressurein the order of the target surface space, the outlet of the firstpressure regulator and the outlet the second pressure regulator. Inaddition, since part of the gas is directly discharged outside at theoutlet of first pressure regulator by the second exhausting apparatus,the amount of gas flowing toward the substrate is decreased to furtherlower the pressure at the outlet of second pressure regulator.Therefore, it is possible to set the pressure in the vicinity of thesubstrate to 8.0×10⁻³ Pa or less, optimal to form high function thinfilms, while the plasma discharge is stably maintained at the pressureof about 3.0×10⁻² Pa in the vicinity of the target.

Two second exhausting apparatuses 12, 12′ are arranged in the sputteringchamber shown in FIG. 7. One exhausting apparatus is arranged behind thecathode 2 and the other is arranged on the sidewall of the vacuumchamber beside the cathode. The structure other than the exhaustingapparatuses is the same as that shown in FIG. 6.

In the sputtering chamber shown in FIG. 8, the second pressure regulator14 comprises a part of the wall of the vacuum chamber. One of exhaustingapparatuses 12, 12′ is arranged behind the cathode and the other isarranged on the wall which is a part of the second pressure regulator.Thus, the arrangement of a plurality of exhausting apparatuses can makelarger pressure difference between the substrate space and the targetspace. Sputtering chambers with two pressure regulators have beenmentioned so far. Sputtering chambers of this invention are notrestricted to these chambers and can have three or more pressureregulator depending on the required pressure in the vicinity of thesubstrate.

In addition, the present invention is applied to not only the so-calledbottom-type magnetoresistance elements as shown in FIG. 9, but also tothe other type elements such a top-type, dual-type and the like.

1. A method of manufacturing a magnetoresistance element comprised of apinned magnetic layer, a non-magnetic intermediate layer, and a freemagnetic layer, the method comprising forming with a sputteringapparatus at least one thin film of said non-magnetic intermediate layerand said free magnetic layer at a pressure of 8.0×10⁻³ Pa or less in thevicinity of a substrate.
 2. The method according to claim 1, whereinsaid sputtering apparatus comprises: a chamber, a cathode configured andpositioned in said chamber to hold a target for forming at least onethin film of said non-magnetic intermediate layer and said free magneticlayer, a substrate holder configured and positioned in said chamber tohold the substrate, a gas introduction mechanism to introduce a gas to atarget space in a vicinity of a surface of the target, a first pressureregulator configured and positioned in said chamber to cause a pressuredifference between said target space and a center space outside saidtarget space, a second exhausting apparatus configured to exhaust saidcenter space and make said center space at a pressure lower than saidtarget space, a second pressure regulator configured and positioned insaid chamber to cause a pressure difference between said center spaceand a substrate space in the vicinity of a surface of the substrate, anda first exhausting apparatus configured to exhaust said substrate spaceand make the said substrate space at a pressure lower than said centerspace.
 3. The method according to claim 2, wherein said first pressureregulator controls a flow of said gas flowing from said target space tosaid center space.
 4. The method according to claim 2, wherein saidfirst pressure regulator is a tapered cylinder member whose diameter isdecreased toward the substrate and is arranged so as to surround saidtarget.
 5. The method according to claim 2, wherein said first pressureregulator is a cylinder member whose end at the substrate side iscovered with a plate having at least one hole and is arranged so as tosurround said target.
 6. The method according to claim 4, wherein saidsecond pressure regulator is a tapered cylinder member whose diameter isdecreased toward the substrate.
 7. The method according to claim 5,wherein said second pressure regulator is a partition member which hasat least one hole and divides an inside of said vacuum chamber.
 8. Themethod according to claim 2, wherein said first and said second pressureregulators each includes a partition member which has at least one holeand divides the inside of said vacuum chamber.